Device and method for registering the use of an odontological instrument

ABSTRACT

The invention concerns a device comprising a mechanism for indicating a value representing current fatigue and devices for modifying the value based on parameters related to the use of the odontological instrument. In a particular embodiment, the devices indicating the fatigue value comprises a washer ( 16 ) connected to the instrument and provided with a certain predetermined number of detachable elements or pre-perforations ( 17 ). Depending on the use of the instrument, for example, its diameter, its taper ratio, the curve of the dental canal to be excavated and the duration of the operation, a certain number of detachable elements are removed or a certain number of pre-perforations are perforated ( 17 ′). When the number of detachable elements or the number of pre-perforations ( 17 ) remaining on the device is less than the number of elements to be detached or perforated on the basis of the predetermined operational parameters, the odontological instrument should no longer be used. The device enables the odontological instrument to avoid being broken in a dental canal.

FIELD OF THE INVENTION

The present invention concerns a device and a method for indication thecurrent fatigue of a odontological instrument having at least a cuttingzone and a handle.

BACKGROUND OF THE INVENTION

In the odontological field surgeons use various instruments to excavatethe dental canal before the introduction of a filling material into saiddental canal.

The instruments to excavate the dental canal have to satisfy very highrequirements. They must be sharp on at least a part of their length andtheir distal end have to be guided easily in the dental canal even whenthe canal has a small curve radius. To avoid the odontologicalinstruments being broken in a dental canal they are mainly used manuallyrather than driven by a motor. Furthermore the screwing effect has to beavoided to reduce the tensions inside of the instruments. For thesereasons this kind of instruments are known to be delicate.

In U.S. Pat. No. 5,628,674 it is known that a nickel and titanium alloyis adequate for the manufacturing of these instruments. It permit therealization of tools being resistant and supple allowing the use ofmotor driven odontological instruments. The instruments made of thisalloy have an important drawback. Due to their resilience and theirsuppleness, the instruments do not present any lasting distortionindicating that they must be replaced. They remain identical and keeptheir aspect even when the limit of fatigue is reached. When the currentfatigue becomes to high the instruments brake without showing anyvisible sign permitting to predict the moment when the braking occurs.Therefore the use of this type of instruments represent a number ofserious problems for surgeons.

SUMMARY OF THE INVENTION

The object of the present invention is to overcome all these drawbacksand to realize a device permitting to give in a simple way an indicationcorresponding to the fatigue of an instrument, so that a user couldreplace the same before it represents a risk of breaking.

This object is reached by the device of the invention, characterized inthat it comprises means connected to said odontological instrumentindicating a value representing the current fatigue of said instrument,means for modifying said value based on parameters relating to the useof the odontological instrument and means for indicating that a limitvalue is reached.

According a preferred embodiment of the device of the invention, saidmeans indicating a value representing the current fatigue of saidinstrument comprise a washer.

According to a first embodiment said washer is provided with apredetermined number of pre-perforations.

According to a second embodiment said washer comprises a predeterminednumber of detachable protrusions.

According to a special embodiment of the device of the invention saidmeans indicating a value representing the current fatigue of saidinstrument comprises a code for identifying said instrument on anunivocal way and for associating a value representing the currentfatigue, and in that the device comprises a storage device formemorizing the current fatigue of each instrument.

According to an advantageous embodiment the device comprises a readingdevice for reading said code.

According to an advantageous embodiment the device comprises a stopwasher said code being placed on said stop washer.

Said code is advantageously a bar-code.

Another object of the invention is a method for indication the currentfatigue of a odontological instrument having at least a cutting zone anda handle, characterized in that it comprises a step of determining thevalue of current fatigue of the odontological instrument, a step ofdetermining the value of fatigue corresponding to a specific use,depending of operational parameters of the instrument, a step ofmodifying the value representing the current fatigue according to thevalue of the fatigue induced by a specific use, depending of operationalparameters of the instrument, a step of comparing the new modified valuerepresenting the new current value of fatigue of the instrument with alimit value.

According an advantageous embodiment of the device of the invention thecurve radius of the dental canal is taken as an operational parameter ofthe instrument.

According another advantageous embodiment of the device of the inventionthe taper ratio of the instrument is taken as a operational parameter ofthe instrument.

According an advantageous embodiment of the device of the invention theduration of the operation corresponding to said specific use is taken asa operational parameter of the instrument.

According to a first manner to apply the method in which theodontological instrument comprises a washer provided with a number ofpre-perforations the step of determining the value of current fatigue ofthe odontological instrument consists in realizing a number ofperforations, this number depending of the value representing fatigueinduced by the specific use.

According to a second manner to apply the method in which theodontological instrument comprises a washer provided with a number ofdetachable protrusions, the step of determining the value of currentfatigue of the odontological instrument consists in detaching a numberof protrusions, this number depending of the value representing fatigueinduced by the specific use.

According to a third manner to apply the method in which theodontological instrument comprises a code, the step of modifying thevalue representing the current fatigue consists in modifying the valuerepresenting the current fatigue in the storage device, according to thevalue representing the fatigue induced by the specific use.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a lateral view of an instrument to excavate a dental canalaccording to the prior art;

FIG. 2 is a lateral view of an instrument to excavate a dental canalaccording to a first embodiment of the device of the invention;

FIG. 3 is an enlarged front view of a washer according to a firstembodiment of the device of the invention;

FIG. 4 is a sectional view along the line A—A of FIG. 3;

FIG. 5 is an enlarged front view of the washer according a secondembodiment of the device of the invention;

FIG. 6 is a sectional view along the line B—B of FIG. 5;

FIGS. 7 to 9 are front views showing various embodiments of the washerof the device of the invention;

FIG. 10 is a front view showing a washer according to another embodimentof the device of the invention;

FIG. 11 shows schematically the use of the device of the inventionprovided with a washer as represented by FIG. 10; and

FIG. 12 a dental canal excavation instrument connected to a dentalsurgical drill.

DETAILED DESCRIPTION OF THE INVENTION

The FIG. 1 shows a odontological instrument 10 as it is used with thedevice of the present invention. The device 10 is provided with a handle11, a cutting zone 12 or a blade whose operational length can be limitedby a stop washer 13. The stop washer 13 is slidingly mounted on thecutting zone. It can also be suppressed. Depending from the use of theodontological instrument the cutting zone 12 may be tapered, the taperratio being generally comprised between two and five degrees.

As shown by the FIGS. 2 to 10, the device 14 of the invention isprovided with means 15 connected to the odontological instrument whichare designed to indicate a value representing the current fatigue ofthis instrument, means to modify this value according to parametersdepending of the use of the odontological instrument and means toindicate that a limit value is reached.

The means 15 for indicating the current value of fatigue comprise awasher 16. According to the embodiments shown by the FIGS. 3 to 6 thewasher comprises pre-perforations 17. As long as the instrument is notused, the current fatigue having a zero value all the pre-perforationsare intact.

When the surgeon uses the instrument for a specific operation he makes avaluation of the fatigue induced by the operation on the instrument.This valuation depends of various use parameters of the instrumentsduring the operation, especially the curve radius of the dental canal tobe excavated, the taper ratio of the instrument and the duration of theoperation.

A fatigue value is attached to the fatigue in accordance with theoperation which is performed by the surgeon: According to theembodiments represented by the figures, the value may vary between oneand twelve, one corresponding to a very low fatigue and twelve to thehighest fatigue. The fatigue value corresponds to the number ofpre-perforations 17 that the surgeon must perforate in the washer. Thereference 17′ on the FIGS. 4 and 5 corresponds to the perforations madeby the surgeon as a consequence of the use of the instrument for a givenoperation.

According to the fatigue value corresponding to a specific operation andto the current value of fatigue of the instrument, the surgeon candecide if the instrument is still adapted to perform the plannedoperation. If the number of pre-perforations which are still intact onthe washer before the planned operation is less than the value offatigue corresponding to that operation, the instrument cannot be usedwithout a risk of rupture. Another instrument must be used.

According to the embodiments shown by the FIGS. 3 to 6 the washercomprises a notch 18 and two arrows 19. These elements are designed toindicate the starting point and the direction of the decrementation. Itis therefore possible to avoid to pierce all the pre-perforations and topierce only the last one. In the case when the fatigue corresponding toa specific operation is six, it would be possible to pierce only thesixth pre-perforation, without piercing all the five previouspre-perforations. Even this solution is not required it may represent asimplification for using the device of the invention.

The FIGS. 7 to 9 show diverse embodiments of the device of theinvention, in which the information corresponding to the current valueof fatigue is represented by a number of detachable protrusions 20.These protrusions are located along the periphery of the washer 16 andmay be realized by an extrusion or a stamping operation.

The base part of these protrusions have a zone of reduced resistance sothat each of them can be easily detached by a surgeon with aconventional tool as a pair of pliers for example. The number of theremaining protrusions correspond to the actual fatigue of theinstrument.

These embodiments permit to visualize immediately the current fatigue ofa odontological instrument.

The FIGS. 10 and 11 show another embodiment of the device of theinvention in which the information relating to the current fatigue maybe disclosed by means of an electronic code reading apparatus 30, forexample a bar code reading device. This type of embodiment isparticularly adapted for instruments having a very high rotation speedwhereby the broken protrusions of the washer may create vibrations ofthe drill. For this kind of device the information relating to thefatigue is not storaged in the instrument but in a separated memorydevice 31.

A bar code 32 is attached to the instrument and located on the stopwasher 13 (see FIG. 1) or on another washer 33 connected to theinstrument. The bar code 32 comprises at least one pre-perforationdesigned to identify the corresponding instrument.

The memory device 31 contains for each instrument a value representingthe current value of fatigue of said instrument and a limit value whichmust not be exceeded.

Before using an instrument for a given operation the surgeon valuatesthe fatigue of the instrument. He will transmit this value to aprocessor 34 which reads the fatigue value of the instrument, modifiesthis value according to the valuated value and compares the modifiedvalue to the limit value.

If the modified value is less than the limit value, the instrument canbe used for the planned operation. If that value is higher, it must beused for another operation inducing a lower fatigue. The current valuecan be displayed by adequate means like a screen 35 of a computer or aliquid crystal screen.

According to the above embodiment the fatigue value may be decrementedfrom an origin value, for example twelve to a limit value, for examplezero. Otherwise, it may also be incremented from an origin value forexample zero to an end or limit value for example one hundred. Such anembodiment would allow to provide a much more finer subdivision of thefatigue value. Contrarily to the embodiments of FIGS. 2 to 9 there areno geometrical restrictions for the representation of the limit value offatigue.

To display a liable information the washer must be attached rigidly tothe instrument and an accidental separation of both parts must beimpossible. Furthermore the washer must be endure sterilizationoperations of the instrument in such a way that the relating informationconcerning fatigue does not risk to be loosed. Silicone is known as anappropriate material adapted to endure all these strains.

The washer may comprise indications for rendering easier the valuationof the fatigue by the surgeon. The color of the washer may representsuch an indication corresponding for example to the taper ratio of theinstrument.

Means 15 for indicating the value of the current fatigue are representedby a washer. Other elements may be adapted for the same function if theydo not induce vibrations to the drill during the operation. Said means15 are provided on a washer 16 which is independent from the stop washer13. The washer 16 and the stop washer 13 could be replaced by a singlewasher integrating both functions.

In the embodiments of FIGS. 10 and 11 the code is a bar code: Othertypes of information coding means may be integrated in the washer 16. Insuch a case an adequate reading device must be used for reading thecoded information.

What is claimed is:
 1. A device for indication a current fatigue of anodontological instrument having at least a cutting zone (12) and ahandle (11), wherein the device comprises: means connected to saidodontological instrument (10) indicating a value representing thecurrent fatigue of said instrument; means for modifying said value basedon parameters corresponding to the use of the odontological instrument;and means for indicating when a limit value is reached.
 2. The deviceaccording to claim 1, wherein said means for indicating (15) a valuerepresenting the current fatigue of said instrument (10) comprises awasher (16).
 3. The device according to claim 2, wherein said washer(16) is provided with a predetermined number of pre-perforations (17).4. The device according to claim 2, wherein said washer (16) comprises apredetermined number of detachable protrusions (20).
 5. The deviceaccording to claim 1, wherein said means for indicating (15) a valuerepresenting the current fatigue of said instrument (100) comprises acode (32) for identifying said instrument on an univocal way and forassociating a value representing the current fatigue, and the devicecomprises a storage device (31) for memorizing the current fatigue ofeach instrument.
 6. The device according to claim 5, wherein said meansfor indicating (15) a value representing the current fatigue of saidinstrument (10) comprises a reading device (30) for reading said code(32).
 7. The device according to claim 5, wherein said means forindicating (15) a value representing the current fatigue of saidinstrument (10) comprises a stop washer (13) and said code (32) isattached to said stop washer.
 8. The device according to claim 5,wherein said code (32) is a bar-code.
 9. A method for indication acurrent fatigue of an odontological instrument having at least a cuttingzone and a handle, wherein the method comprises the steps of:determining a value of the current fatigue of the odontologicalinstrument; determining the value of fatigue corresponding to a specificuse, depending of operational parameters of the instrument, modifyingthe value representing the current fatigue according to the value of thefatigue induced by a specific use, depending from operational parametersof the instrument, comparing the new modified value representing the newcurrent value of fatigue of the instrument with a limit value.
 10. Themethod according to claim 9, further comprising the step of taking aradius of a dental canal as an operational parameter of the instrument.11. The method according to claim 9, further comprising the step oftaking a taper ratio of the instrument as an operational parameter ofthe instrument.
 12. The method according to claim 9, further comprisingthe step of taking a duration of the operation corresponding to saidspecific use as an operational parameter of the instrument.
 13. Themethod according to claim 5, further comprising the step of using anodontological instrument (10) which comprises a washer (16) providedwith a number of perforations (17), wherein the step of determining thevalue of current fatigue of the odontological instrument comprisesrealizing a number of perforations (17), in which the number ofperforations (17) depends on the value representing fatigue induced bythe specific use.
 14. The method according to claim 9, furthercomprising the step of using an odontological instrument (10) whichcomprises a washer (16) provided with a number of detachable protrusions(20), wherein the step of determining the value of current fatigue ofthe odontological instrument comprises detaching a number ofprotrusions/(20), in which the number of protrusions (20) depends on thevalue representing fatigue induced by the specific use.
 15. The methodaccording to claim 9, further comprising the step of using anodontological instrument (10) which comprises a code (32), wherein thestep of modifying the value representing the current fatigue comprisesmodifying the value representing the current fatigue in the storagedevice (31), according to the value representing the fatigue induced bythe specific use.